Stars were able to slow down their own aging
Scientists using data from the Hubble telescope discovered a new fact about white dwarf stars. It turned out that they are able to slow down the rate of their aging, reports Nature Astronomy.
White dwarfs are the slowly cooling cores of stars that have previously lost their outer envelope. It is believed that 98% of the stars in the Universe, including the Sun, will reach this stage at the end of their existence.
Scientists have long called white dwarfs “dead” stars. But a new study has shown that they can maintain stable thermonuclear activity.
To better understand the evolution of white dwarfs, astronomers compared the cooling of white dwarfs in two massive globular clusters, M3 and M13. These clusters are similar in many ways, but contain different types of stars: they are hotter in M13.
Scientists have studied about 700 cosmic bodies in both clusters. It turned out that white dwarfs from M3 behave as expected – they do not show activity and slowly cool down. But some of the dwarfs from M13 were able to retain an outer shell of hydrogen, which allowed them to burn longer and cool down more slowly.
A computer model has shown that approximately 70% of white dwarfs sustain hydrogen burning at the surface, which slows down the cooling rate. This discovery is important for astronomers who measure the age of stars in the Milky Way.
Previously, scientists determined the age of a white dwarf based on its cooling rate. But the study has shown that these estimates can be wrong by a billion years.
“We are now examining other clusters like M13 to determine the conditions that cause stars to maintain a thin hydrogen envelope and age slowly,” the authors noted.
Previously, scientists talked about a new type of supernova. It arises from the collision of living and dead stars.
